1. Field of the Invention
Embodiments of the invention relate to touch sensor integrated type display devices, in particular touch sensor integrated type display devices capable of improving touch sensibility.
2. Discussion of the Related Art
In recent years, flat panel displays (hereinafter referred to as “display devices”), which are able to be manufactured as a large-sized display device at a low price and have high display quality (including capability of displaying a motion picture, resolution, brightness, contrast ratio, color representation capability, etc.), have been developed to meet the needs capable of appropriately displaying multimedia with the development of the multimedia. Various input devices, such as a keyboard, a mouse, a track ball, a joystick, and a digitizer, have been used to allow a user to interface with the flat panel display devices.
However, when the user makes use of these input devices, the user's dissatisfaction increases because the user is required to learn how to use the input devices and the input devices occupy space, thereby making it difficult to achieve a high level of completeness in the products. Thus, a demand for a convenient and simple input device for the display device capable of reducing erroneous operations is increasing. In response to the increased demand, a touch sensor has been proposed to recognize information when the user inputs the information by directly touching the screen or approaching the screen with his or her hand or a pen while he or she watches the display device.
The touch sensor has a simple configuration capable of reducing the erroneous operations. The user can also perform an input action without using a separate input device and can quickly and easily manipulate a display device through the contents displayed on the screen. Thus, the touch sensor has been applied to various display devices.
The touch sensor may be classified into an add-on type touch sensor, an on-cell type touch sensor, and an integrated type (or in-cell type) touch sensor, depending on its structure. The add-on type touch sensor may be configured such that the display device and a touch panel including the touch sensor are individually manufactured, and then the touch panel may be attached to an upper substrate of the display device. The on-cell type touch sensor may be configured such that the touch sensor may be directly formed on the surface of an upper glass substrate of the display device. The integrated type touch sensor may be configured such that the touch sensor may be mounted inside the display device to thereby achieve a thin profile display device and increase the durability of the display device.
In the integrated type touch sensor, it is possible to provide advantages of a thin profile and an improvement in durability because common electrodes of the display device are shared with touch electrodes of the touch sensor.
Accordingly, the integrated type touch sensor has caught attention in that it is possible to achieve a thin shape of the display device and enhance a durability of the display device, thereby resolving the problems of the add-on type and on-cell type touch sensors. The integrated type touch sensor may be divided into an optical touch sensor and a capacitive touch sensor, depending on a method for sensing a touched portion. The capacitive touch sensor may be subdivided into a self capacitive touch sensor and a mutual capacitive touch sensor.
The self capacitive touch sensor may have a plurality of independent patterns in a touch area of a touch sensing panel, and changes in a capacitance of each independent pattern are measured, thereby deciding whether or not a touch operation is performed. The mutual capacitive touch sensor may have X-axis direction electrode strings (for example, driving electrode strings) and Y-axis direction electrode strings (for example, sensing electrode strings) which cross over each other in the touch area of the touch sensing panel to form a matrix, applies a driving pulse to the X-axis electrode strings, and senses changes in voltages generated in sensing nodes defined as the crossings of the X-axis direction electrode strings and the Y-axis direction electrode strings through the Y-axis direction electrode strings, thereby deciding whether or not a touch operation is performed.
However, in the mutual capacitive touch sensor, a mutual capacitance between the X-axis direction electrode strings and the Y-axis direction electrode strings is small, but parasitic capacitance generated in the data lines and gate lines arranged in the display device are large. Accordingly, there are some problems making difficult to decide accurate touch positions in the mutual capacitive touch sensor.
Also, the mutual capacitive touch sensor necessarily has complicated routing wire construction because it has to have touch driving routing wires connected to touch driving electrode strings (for example, the X-axis direction electrode strings) and touch sensing routing wires connected to touch sensing electrode strings (for example, the Y-axis direction electrode strings) for multi-touch perception.
For the reason mentioned above, the self capacitive touch sensor with a simple routing wire construction and a high touch sensibility was widely used.
Hereinafter, a related art self capacitive touch sensor integrated type liquid crystal display device (hereinafter, simply referred to as “touch sensor integrated type display device”) is described with reference to FIGS. 1 to 3. FIG. 1 is a planar view showing the related art touch sensor integrated type display device, FIG. 2 is a planar view showing a region R1 shown in FIG. 1, and FIG. 3 is a planar view showing a region R2 shown in FIG. 2.
Referring to FIG. 1, the touch sensor integrated display device includes an active area AA, in which touch electrodes are arranged and data are displayed, and a bezel area BA positioned outside the active area AA. In the bezel area BA, various wires and a source and touch driving integrated circuit 10 are disposed.
The active area AA includes a plurality of touch electrodes Tx11 to Tx15, Tx21 to Tx25, . . . , and Tx81 to Tx85, and a plurality of touch routing wires TW11 to TW15, TW21 to TW25, . . . , and TW81 to TW85 connected to the plurality of touch electrodes Tx11 to Tx15, Tx21 to Tx25, . . . , and Tx81 to Tx85, respectively. The plurality of touch electrodes Tx11 to Tx15, Tx21 to Tx25, . . . , and Tx81 to Tx85 are divided in a first direction (e.g. x-axis direction) and a second direction (e.g. y-axis direction) which cross each other. The plurality of routing wires TW11 to TW15, TW21 to TW25, . . . , and TW81 are arranged in parallel to each other along the second direction.
The plurality of touch electrodes Tx11 to Tx15, Tx21 to Tx25, . . . , and Tx81 to Tx85 are formed by dividing a common electrode of a display device. The plurality of touch electrodes Tx11 to Tx15, Tx21 to Tx25, . . . , and Tx81 may be operated as common electrodes during a display mode for displaying data, and operated as touch electrodes during a touch mode for perceiving touch positions.
The touch driving integrated circuit 10 disposed in bezel area BA supplies display data to data lines in synchronization with driving of gate lines (not shown) of the display, and supplies a common voltage to the touch electrodes Tx11 to Tx15, Tx21 to Tx25, . . . , and Tx81 to Tx85 during the display mode. Also, the integrated circuit 10 supplies a touch driving voltage to the touch electrodes Tx11 to Tx15, Tx21 to Tx25, . . . , and Tx81 to Tx85, and determines touch positions at which touches are performed by scanning changes of capacitance in touch electrodes before and after the touch is performed during the touch mode. The various wires disposed in bezel area BA include the touch routing wires TW11 to TW15, TW21 to TW25, . . . , and TW81 to TW85, gate lines and data lines (not shown) extended from the active area AA and connected to the integrated circuit 10.
Referring to FIGS. 2 and 3, the related art touch sensor integrated type display device includes thin film transistors TFT disposed on a substrate SUB, pixel electrodes P11 to P44 respectively connected to drain electrodes of the thin film transistors TFT, and a touch electrode Tx11 disposed to overlap the pixel electrodes P11 to P44, thereby generating a horizontal electric field between the pixel electrodes P11 to P44 and the touch electrode Tx11.
The thin film transistors TFT each includes a gate electrode GE extended from a gate line GL formed on the substrate SUB, a semiconductor active layer A disposed on a gate insulation layer GI covering the gate line GL and gate electrode GE to overlap a portion of the gate line GL, and a source electrode SE and a drain electrode DE disposed on the semiconductor active layer A and separated from each other at a predetermined distance. The source electrode SE is extended from a data line DL disposed on the gate insulation layer GI.
The pixel electrode Px is disposed on a second insulation layer INK on first insulation layer INS1 covering the thin film transistor TFT. The pixel electrode Px is connected to the drain electrode DE of the thin film transistor TFT exposed via first contact hole CH1 passing through the first and second insulation layers INS1 and INS2.
The pixel electrode Px is covered with a first passivation layer PAS1. The touch routing wire TW11 is arranged on the first passivation layer PAS1 to overlap a data line DL. The touch routing wire TW11 is covered with a second passivation layer PAS2.
The touch electrode Tx11 is disposed on the second passivation layer PAS2 and connected to the touch routing wire TW11 via a second contact hole CH2 passing through the second passivation layer PAS2. The touch electrode Tx11 has a plurality of slits to generate a horizontal electric field together with the pixel electrode Px.
In the touch sensor integrated type display device, when a user makes fingers or stylus pens to contact the active area AA, it is possible to perceive the touch positions by measuring changes of capacitance on touch electrodes before and after the touch is performed.
However, in the touch sensor integrated type display device, different signals are supplied at different times to the touch electrodes during the display operation period and the touch operation period because the touch electrodes are operated as common electrodes or touch electrodes in such a time-division method. That is, a common voltage is supplied to the touch electrodes during the display operation period, and a touch driving pulse is supplied to the touch electrodes during the touch operation period. Accordingly, there are some problems such as incorrect operations of the touch sensor integrated type display device by a ripple voltage generated to the touch electrodes due to the touch driving pulse.
Furthermore, the touch electrodes suffer from adverse affection due to various capacitance components generated by the gate line, the data line, pixel electrode and so on, during the touch operation period. In particular, when display patterns are changed from white to black or black to white, a basic value of raw data sensing a touch performance may be varied due to the various capacitance components, thereby generating a DTX (Display to Touch Crosstalk) phenomenon in which a touch is perceived although no touch was performed.